Structural and dielectric properties of A(Fe1/2Ta1/2)O3 [A = Ba, Sr, Ca]

The complex perovskite oxide barium iron tantalate (BFT), BaFe1/2Ta1/2O3, strontium iron tantalate (SFT), SrFe1/2Ta1/2O3 and calcium iron tantalate (CFT), CaFe1/2Ta1/2O3 are synthesized by a solid-state reaction technique. Rietveld refinement of the X-ray diffraction data of the samples shows that BFT and SFT crystallize in cubic structure, with lattice parameter a = 4.06 Å for BFT and 3.959 Å for SFT, whereas CFT crystallizes in orthorhombic structure having lattice parameters a = 5.443 Å, b = 5.542 Å and c = 7.757 Å. Fourier transform infrared spectra show two primary phonon modes of the samples at around 450 cm−1 and 620 cm−1. The compounds show significant frequency dispersion in its dielectric properties. The complex impedance plane plots of the samples show that the relaxation (conduction) mechanism in these materials is purely a bulk effect arising from the semiconductive grains. The relaxation mechanism of the samples is modelled by Cole–Cole equation. The frequency dependent conductivity spectra are found to follow the power law.

Graphical abstractFTIR spectra of BFT, SFT and CFT at room temperature.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► The structural and dielectric properties of BaFe1/2Ta1/2O3, SrFe1/2Ta1/2O3 and CaFe1/2Ta1/2O3. ► Fourier transform infrared spectra show two primary phonon modes of the samples at around 450 cm−1 and 620 cm−1. ► The compounds show significant frequency dispersion in its dielectric properties. ► The relaxation mechanism of the samples is modelled by Cole–Cole equation.